Engines may be cooled by circulating coolant fluid such as water through passageways in the engine. In the event of a cooling system degradation (e.g. water pump degradation) or loss of coolant (e.g. due to coolant system leak), engine metal components may overheat.
Gebby et al. (U.S. Pat. No. 7,204,235) address engine overheating in the event of cooling system degradation by alternately shutting down the fuel injectors to each bank of engine cylinders and air-cooling the deactivated engine cylinder bank with un-combusted intake air. Alternately deactivating each bank of cylinders can provide some engine torque for vehicle operation.
The inventors herein have recognized potential issues with the above approach. Namely, with turbocharged and other high-specific power output engines, traditional fail-safe cooling strategies, such as alternate deactivation and air-cooling of engine cylinder banks, may not maintain cylinder head temperatures below engine metal melting temperatures. Consequently, turbocharged engines are often disabled soon after initiation of traditional fail-safe cooling strategies. Furthermore, even if some cylinders maintain combustion during the cooling, the engine may not provide enough torque to sustain vehicle operability and vehicle driveability, particularly in turbocharged engines.
One approach that addresses the aforementioned issues is a method for a fail-safe cooling strategy (FSC), comprising deactivating one or more engine cylinders while limiting engine cylinder load in response to cooling system degradation and/or coolant loss in a turbocharged engine. Furthermore, the method may comprise deactivating one or more engine cylinders while limiting engine cylinder load in response to an engine cylinder temperature exceeding a second threshold temperature. The number of deactivated cylinders and the load limit may be chosen based on increasing torque while maintaining engine speed below a threshold engine speed, and maintaining engine cylinder temperatures below a third threshold temperature, the third threshold temperature greater than the second threshold temperature. In this manner, overheating of engine metal components can be reduced while sustaining vehicle operability and driveability.
The above advantages and other advantages, and features of the present description will be readily apparent from the following Detailed Description when taken alone or in connection with the accompanying drawings.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.